I have been working on making some plans for a major home improvement project, using QCAD Pro. Part of this includes doing a radiant heating system retrofit, which means I need to draw a bunch of hydronic heating system layout diagrams.

I was not able to find any sources for reasonably priced .dxf compatible hydronic symbol libraries, so I've been working on creating my own. In order to make my work available to others, I would like to release it as Open Source, probably using the GPLv3 license.

According to the Free Software Foundation, the best way to apply the GPL is to put a statement into each source file - in this case the .DXF files that make up the library. I am trying to figure out how to insert comments into a .DXF file - I have found something about a "Group 999" tag for comments in the AutoDesk documentation stuff on their website, and I notice that at least some of the files in the QCAD parts library start out with

as the first three lines in the file, but I can't find any real guides as to what the rules are for inserting comments...
1. What are the limits for line length?
2. Any restrictions on characters as long as I stick w/ normal ASCII?
3. What do I do if I need multiple comment lines?
4. Is the zero on the third line something I need to put, or is it the start of the next section?
etc...
Also, are there any issues w/ putting a non-.DXF file in the library directory - i.e. a "licenses.txt" file and a "read-me.txt" for instance?

A second question, is there a hosting location that anybody could reccomend as a place to use for distributing this kind of library? There are all sorts of "sourceforge" type sites for software programs, but this isn't quite a program, so I'm not sure if I would be able to use them or not.

I am new to QCad so I am just starting to learn about blocks and would appreciate any basic info on acquiring and importing blocks into a drawing. I run Ubuntu (Debian) 9.04 and QCad community 2.0.5

I did the exact same thing as you, but drew up my mechanical system in an old version of Visio. I'd be happy to send you my design if you like, it works perfectly and was very cheap since I used a standard $300 hot water heater for my closed system radiant floor. Don't let a plumber talk you into a $1500 boiler, you don't need it!

Thanks for that link - it looks like it could have a lot of useful things in it, though it's hard to tell (I didn't see an easy way to get thumbnails to preview the drawings)

However I'm slowly working my way towards being able to release this library as an open source thing... I'm a strong believer in free software, and want to be as sure as I can that the work I've put into this set of blocks doesn't get sucked into some proprietary product - directly releasing it under the GPL is the best way I know of to do this.

1. I've applied for a project listing on the FSF's Savannah website - am waiting to hear back if they will accept it, since this kind of library isn't exactly a "program" or "documentation"

2. I have finally (I think) figured out how to put comment text into a .dxf file - so I can put the appropriate FSF recommended copyright and license statements in them

3. I've started building all the other elements I need to make the complete tarball...

Hopefully I'll be ready to push this out as soon as / if the FSF approves my application... If they don't I'll have to find a different site. I may ask at the CAD-tastrafy website if Savannah doesn't work out.

On the heating system itself, what I'm wanting to do is a setup with a Gasification Wood Boiler, as you can see them talking about quite a bit in the "Boiler Room" on Hearth.com where I'm one of the moderators. That is considerably more money than a water heater, or even most fossil boilers, but a good gasifier setup, w/ a solar water tie-in can essentially let you be carbon neutral, and free from dependence on oil or gas for your heat and hot water needs... One of our hearth.com members went from 800 gallons a year to 12 (because he went on a vacation trip)

I have figured out how to put comments into a .dxf file, using the 999 group code, but I can't get them to STAY in the file - if I put the comments in with a text editor (vim) it looks fine and the file opens. But when I open the file w/ QCAD and save it again, without making any changes, my comment lines are erased...

I have posted another thread on this, hopefully Andrew or one of the other system mods will answer...

I wonder if you are not making things more complicated than they have to be. Many file formats don't have the possibility to include license information inside the format (in a reasonable way) and yet, files of any format can be released under whatever license you want.